A cana-de-açúcar constitui-se em uma importante atividade agrícola no Brasil, sendo que sua produtividade relaciona-se a vários fatores, entre os quais a disponibilidade de quantidades adequadas de nutrientes, com destaque para o nitrogênio. Entretanto, o constante uso de fertilizantes aumentam a possibilidade de contaminação ambiental, principalmente de corpos de água. No presente trabalho foram avaliados o comportamento do N inorgânico e demais íons majoritários dissolvido presentes nas águas superficiais e sub-superficiais em áreas cultivadas com cana-de-açúcar, considerando as contribuições atmosféricas, e suas implicações ambientais. Em área experimental localizada no município de Santa Cruz das Palmeiras, SP, foram coletadas amostras de água em quatro pontos: pluviômetro, Ribeirão dos cocais, extrator de solução do solo e lençol freático; e analisadas por cromatografia iônica e microtitulação de Gran. Os principais íons majoritários foram caracterizados para cada ponto de amostragem considerando além de suas concentrações, a variabilidade sazonal e os transportes de carga dissolvida e potencial de perdas por lixiviação ao longo do período estudado. Observou-se que as águas de chuva e do Ribeirão dos Cocais apresentaram as menores concentrações iônicas, com um Total de Sólidos Dissolvidos (TDS) médio de 5,28 e 3,71 mg L-1, respectivamente; a solução do solo as maiores concentrações, com TDS médio variando de 78,67 a 130,56 mg L-1; e, as águas do lençol freático concentrações com valores intermediários, com TDS médio de 12,72 mg L-1. A participação dos íons nitrogenados dissolvidos no TDS foi de 17,87% para as águas de chuva, com picos de concentração dos íons NO3- e NH4+ no início dos períodos chuvosos; para os demais pontos de amostragem essa participação foi inferior a 5%, sem variações significativas ao longo do período estudado. Entre os íons nitrogenados, o NO3- foi a espécie de maior participação no TDS em todos os pontos de amostragem, com aportes atmosféricos na ordem de 35,68 kg a-1 em 2006 e 34,66 kg a-1 em 2007, e um transporte fluvial médio estimado de 46,16 kg para o período de cheia em 2007, o que representou o dobro da estimada para o período de estiagem do mesmo ano e correspondeu a 82% do NID transportado no período. Foi possível verificar também que durante o período de amostragem de solução do solo, janeiro a abril de 2006, os fluxos de água foram sempre descendentes, indicando um potencial de perdas por lixiviação na ordem de 2,94 kg ha-1 no período para os íons nitrogenados, com destaque para o NO3- com 1,59 kg ha-1 no período. As razões íon/Cl- estabelecidas mostraram que houve influência dos aportes terrestres locais nas águas de chuva e evidenciaram o controle dos aportes atmosféricos totais (chuva) sobre as águas do Ribeirão dos Cocais e do lençol freático, além de indicarem que não ocorreu a lixiviação da solução do solo para o lençol freático. Ainda assim, os riscos de contaminação associadas à cultura da cana-de-açúcar não podem ser desconsiderados, indicando a necessidade de mais estudos / The sugar cane is an important agricultural activity in Brazil and its productivity is related to several factors, such as the availability of suitable nutrients quantities, with emphasis on the nitrogen. However, the constant use of fertilizers increases the possibility of environmental contamination, mainly in water bodies. In this study were evaluated the inorganic N performance and other major dissolved ions present in surface and sub-surface waters in sugar cane areas, considering the atmospheric contributions and its environmental implications. In the experimental area, located in the municipality of Santa Cruz das Palmeiras, Brazil, were collected water samples in four points: pluviometer, Cocais stream, soil solution extractors and groundwater, which were analyzed by ionic chromatography and Gran microtitration. The major ions were characterized for each sampling point considering, beyond their concentrations, their seasonal variability and the dissolved loads transports and potential for loss by leaching during the studied period. It was observed that the waters samples from rain and Cocais stream had the lowest ionic concentrations, with average Total Dissolved Solids (TDS) of 5.28 and 3.71 mg L-1, respectively; soil solution presented the greatest concentrations, with average TDS ranging from 78.67 to 130.56 mg L-1, and in the groundwater samples the concentrations presented intermediate values, with TDS mean of 12.72 mg L-1. The participation of dissolved nitrogen ions in TDS was 17.87% for the rain waters, with concentration peaks for NO3- and NH4+ at the beginning of the rainy periods; for other sampling points such participation was less than 5%, without significant changes over the studied period. Among the nitrogen ions, the NO3- had the higher participation in TDS for all the sampling points, with atmospheric inputs of 35.68 kg y-1 in 2006 and 34.66 kg y-1 in 2007, and an average stream transport of 46.16 kg for the high water period in 2007, which was twice higher than the estimative for the low water period in the same year corresponding to 82% of the transported NID in this period. It was also verified that during the soil solution sampling, January to April 2006, the water flows had always descending movement, indicating a loss potential by leaching about 2.94 kg ha-1 for the nitrogen ions in the period emphasizing the NO3- with 1.59 kg ha-1. The íon/Cl- ratios showed that there was influence of the local land contributions in the rain waters and they demonstrated the control of the atmospheric total contributions (rain) in the waters of Cocais stream and groundwater, in addition, they also indicated that there was not soil solution leaching to the groundwater. Yet, the risks of contamination associated with the sugar cane plantations can not be disregarded, indicating the need for more studies

A modelagem da dinâmica de solutos no solo tem se mostrado uma ferramenta essencial, pois permite simular cenários e prever impactos ao meio ambiente associados ao manejo inadequado de fertilizantes agrícolas. Na zona radicular das culturas a parametrização do transporte de solutos, bem como a parametrização física do solo, são de difícil determinação tornando a sua modelagem onerosa e imprecisa. Portanto, a presente pesquisa teve como objetivo avaliar a performance do modelo SWAP (Soil, Water, Atmosphere and Plant), em simular a extração da solução do solo pela cultura do milho, em ambiente protegido. O ambiente de estudo ficou restrito à rizosfera da cultura do milho ao longo de seu ciclo de desenvolvimento, mediante a aplicação de uma solução de nitrato de potássio via água de irrigação. Para isso, conduziu-se um experimento em ambiente protegido, cujo cultivo do milho foi feito em 18 lisímetros de drenagem de 500L com plantio de duas covas por lisímetro (plantio em 22/11/2014 e colheita em 22/02/2015). Os valores de umidade volumétrica do solo e de condutividade elétrica da solução do solo foram registrados pela TDR (Time Domain Reflectometry), sendo monitorados em 4 profundidades ao longo da secção transversal das raízes (5, 15, 25 e 35 cm). Também foram monitoradas variáveis agrometeorológicas a fim de se descrever as condições experimentais. Os valores simulados pelo modelo SWAP foram confrontados com os dados observados, registrados pela TDR. A avaliação da performance do modelo foi feita pelo emprego do índice de concordância (Id), índice de avaliação de modelos (E), raíz quadrada média do erro (RMSE) e coeficiente de determinação. Diante dos resultados obtidos, percebeu-se pelo monitoramento agrometeorológico que o ciclo da cultura se deu em condições de anomalias climáticas, isso de certa forma influenciou na extração de água pela cultura. A simulação da extração de água na rizosfera do milho pelo modelo SWAP demonstrou uma satisfatória performance do modelo, o qual apresentou resultado pelos índices de avaliação valores superiores a 0,7 e índices de concordância superiores a 0,9 para todas as camadas monitoradas. O erro quadrático médio foi inferior a 0,009 cm3 cm-3 para todas as camadas, apesar de ter nas camadas mais profundas uma atenuação qualitativa na simulação. O movimento da extração da solução do solo na rizosfera, em especial, nas camadas superficiais apresentaram resultados satisfatórios com índices de avaliação de modelos de 0,659 e 0,596 e índices de concordância de 0,913 e 0,834, respectivamente, para as camadas de 5 e 15 cm de profundidade. Já para as camadas mais profundas não se observou boa aderência do valor simulado aos dados. O coeficiente de extração relativa da solução do solo pelo milho apresentou valor de 16%. Assim, o modelo SWAP mostrou-se satisfatório na simulação do movimento da solução do solo na zona radicular da cultura do milho, mesmo sob condições atmosféricas extremas. Não obstante, seu desempenho foi prejudicado para as simulações em camadas inferiores, onde foi observada uma baixa variação do conteúdo de água e concentração de sais no solo. / The modeling of solute dynamics in soil is an essential tool for simulating scenarios and predicting environment impacts associated with inadequate management of fertilizers. Solute transport parameter and soil physical parameters in the vadose zone are difficult to determine, causing modeling to be expensive and imprecise. This research, therefore, was set up to evaluate the effectiveness of the SWAP (Soil, Water, Atmosphere and Plant) model to simulate soil solution uptake by corn under controlled environmental conditions. The study consisted of applying a potassium nitrate solution in irrigation water to maize rhizosphere throughout its development cycle. The experiment was conducted in a greenhouse, in which maize was planted on 11/22/2014 and harvested on 02/22/2015 in eighteen 500L drainage lysimeters.The soil moisture values and electrical conductivity of soil solution were registered by TDR (Time Domain Reflectometry) at four depths (5, 15, 25 and 35 cm) along the cross-section of the root. Environmental variables were also monitored in order to characterize the experimental conditions. Values simulated by the SWAP model were compared with observed data recorded by the TDR. Model performance was evaluated by the use of the Concordance Index (Id), the Model Assessment Index (E), Root Mean Square Error (RMSE), and Coefficient of Determination. As the experiment was conducted under controlled conditions, the water uptake patterns might not be reflective of uptake patterns under normal weather conditions. The simulation of water extraction in the rhizosphere of corn by SWAP model matched observed values, with indices greater than 0.7 and concordance rates of over 0.9, for all monitored layers. The RMSE was less than 0.009 cm3 cm-3 for all layers. The concentration of extracts of the soil solution in the rhizosphere, in particular in the top two layers, were satisfactorily simulated with model evaluation indexes of 0.659 and 0.596, and concordance rates of 0.913 and 0.834, respectively, for the 5 and 15 cm layers. For the deeper layers, there was little correlation between the observed and simulated value. The relative extraction coefficient of soil solution for corn was 16%. Thus, the SWAP model satisfactorily simulated soil solution movement in the upper layers of the vadose zone of maize, even under extreme weather conditions. However, the model did not perform as well in the lower layers performance was impaired for the simulations in lower layers, which had low variation in the observed water content and salt concentration in the soil.

A cana-de-açúcar constitui-se em uma importante atividade agrícola no Brasil, sendo que sua produtividade relaciona-se a vários fatores, entre os quais a disponibilidade de quantidades adequadas de nutrientes, com destaque para o nitrogênio. Entretanto, o constante uso de fertilizantes aumentam a possibilidade de contaminação ambiental, principalmente de corpos de água. No presente trabalho foram avaliados o comportamento do N inorgânico e demais íons majoritários dissolvido presentes nas águas superficiais e sub-superficiais em áreas cultivadas com cana-de-açúcar, considerando as contribuições atmosféricas, e suas implicações ambientais. Em área experimental localizada no município de Santa Cruz das Palmeiras, SP, foram coletadas amostras de água em quatro pontos: pluviômetro, Ribeirão dos cocais, extrator de solução do solo e lençol freático; e analisadas por cromatografia iônica e microtitulação de Gran. Os principais íons majoritários foram caracterizados para cada ponto de amostragem considerando além de suas concentrações, a variabilidade sazonal e os transportes de carga dissolvida e potencial de perdas por lixiviação ao longo do período estudado. Observou-se que as águas de chuva e do Ribeirão dos Cocais apresentaram as menores concentrações iônicas, com um Total de Sólidos Dissolvidos (TDS) médio de 5,28 e 3,71 mg L-1, respectivamente; a solução do solo as maiores concentrações, com TDS médio variando de 78,67 a 130,56 mg L-1; e, as águas do lençol freático concentrações com valores intermediários, com TDS médio de 12,72 mg L-1. A participação dos íons nitrogenados dissolvidos no TDS foi de 17,87% para as águas de chuva, com picos de concentração dos íons NO3- e NH4+ no início dos períodos chuvosos; para os demais pontos de amostragem essa participação foi inferior a 5%, sem variações significativas ao longo do período estudado. Entre os íons nitrogenados, o NO3- foi a espécie de maior participação no TDS em todos os pontos de amostragem, com aportes atmosféricos na ordem de 35,68 kg a-1 em 2006 e 34,66 kg a-1 em 2007, e um transporte fluvial médio estimado de 46,16 kg para o período de cheia em 2007, o que representou o dobro da estimada para o período de estiagem do mesmo ano e correspondeu a 82% do NID transportado no período. Foi possível verificar também que durante o período de amostragem de solução do solo, janeiro a abril de 2006, os fluxos de água foram sempre descendentes, indicando um potencial de perdas por lixiviação na ordem de 2,94 kg ha-1 no período para os íons nitrogenados, com destaque para o NO3- com 1,59 kg ha-1 no período. As razões íon/Cl- estabelecidas mostraram que houve influência dos aportes terrestres locais nas águas de chuva e evidenciaram o controle dos aportes atmosféricos totais (chuva) sobre as águas do Ribeirão dos Cocais e do lençol freático, além de indicarem que não ocorreu a lixiviação da solução do solo para o lençol freático. Ainda assim, os riscos de contaminação associadas à cultura da cana-de-açúcar não podem ser desconsiderados, indicando a necessidade de mais estudos / The sugar cane is an important agricultural activity in Brazil and its productivity is related to several factors, such as the availability of suitable nutrients quantities, with emphasis on the nitrogen. However, the constant use of fertilizers increases the possibility of environmental contamination, mainly in water bodies. In this study were evaluated the inorganic N performance and other major dissolved ions present in surface and sub-surface waters in sugar cane areas, considering the atmospheric contributions and its environmental implications. In the experimental area, located in the municipality of Santa Cruz das Palmeiras, Brazil, were collected water samples in four points: pluviometer, Cocais stream, soil solution extractors and groundwater, which were analyzed by ionic chromatography and Gran microtitration. The major ions were characterized for each sampling point considering, beyond their concentrations, their seasonal variability and the dissolved loads transports and potential for loss by leaching during the studied period. It was observed that the waters samples from rain and Cocais stream had the lowest ionic concentrations, with average Total Dissolved Solids (TDS) of 5.28 and 3.71 mg L-1, respectively; soil solution presented the greatest concentrations, with average TDS ranging from 78.67 to 130.56 mg L-1, and in the groundwater samples the concentrations presented intermediate values, with TDS mean of 12.72 mg L-1. The participation of dissolved nitrogen ions in TDS was 17.87% for the rain waters, with concentration peaks for NO3- and NH4+ at the beginning of the rainy periods; for other sampling points such participation was less than 5%, without significant changes over the studied period. Among the nitrogen ions, the NO3- had the higher participation in TDS for all the sampling points, with atmospheric inputs of 35.68 kg y-1 in 2006 and 34.66 kg y-1 in 2007, and an average stream transport of 46.16 kg for the high water period in 2007, which was twice higher than the estimative for the low water period in the same year corresponding to 82% of the transported NID in this period. It was also verified that during the soil solution sampling, January to April 2006, the water flows had always descending movement, indicating a loss potential by leaching about 2.94 kg ha-1 for the nitrogen ions in the period emphasizing the NO3- with 1.59 kg ha-1. The íon/Cl- ratios showed that there was influence of the local land contributions in the rain waters and they demonstrated the control of the atmospheric total contributions (rain) in the waters of Cocais stream and groundwater, in addition, they also indicated that there was not soil solution leaching to the groundwater. Yet, the risks of contamination associated with the sugar cane plantations can not be disregarded, indicating the need for more studies

Reverse Osmosis (RO) is widely accepted as an alternative method to produce freshwater from different feed water sources. This technology competitively substitutes the thermal processes in the near future because of several advantages particularly in energy saving. The success of RO operation will, however, depends largely on the overall membrane performance. Deposit or build-up of solute is one of the main reasons for membrane operation failure. Build-up of solute or deposit which is known as fouling and scaling will decrease the permeate flux and increase the energy consumption in particular after prolonged operation of RO. The thesis presents the experimental results obtained in a small-scale RO system. The aim of this study is to investigate the effect of sodium chloride and calcium carbonate on the membrane performance and subsequent build-up of solute on the membrane surface. The experiments were carried out in a small-scale of RO (2 m3/day capacity) with spiral wound membrane using simulated feed water, secondary effluent, and groundwater samples. The parameters chosen for the experiments are applied pressure (1250-4750 kPa), and concentration of sodium chloride (l00-5000 mg/L) and calcium carbonate (50-100 mg/L). / The results from feedwater runs indicated that initial sodium chloride and calcium carbonate in feed water and applied pressure affects the overall membrane performance. However, there is no significant effect on membrane performance for sodium chloride with concentration below 1200 mg/L and applied pressure lower than 2250 kPa. Applied pressure appears to have an impact on build-up of sodium and calcium on the membrane surface for pressures greater than 2750 kPa. For typical small-scale RO system used in this experiment, build-up of calcium will slightly decrease with given pressure caused by the characteristic of membrane that easily removes the divalent ions. The osmotic pressure of solution also strongly affects the permeate flow rate in particular for relatively higher sodium concentration (> 2500 mg/L). As a consequence of higher osmotic pressure, zero permeate flux is achieved when sodium chloride concentration was greater than 5000 mg/L and applied pressure lower than 1750 kPa. Results also indicated that fouling might pose a potential problem in small-scale RO operation. In order to investigate the membrane performance, experiments with secondary effluent samples were also performed. Results indicated that water recovery percentages and permeate flux also linearly increase with applied pressure. However, effectiveness of membrane decreases less than 98% otherwise build-up of solute tends to increase. It is suggested that lower values of the water recovery percentage (WRP) and permeate flux (Jw) are caused by the characteristic of secondary effluent that have high-suspended solids, organic carbon, and minerals. Further, the membrane performance also examined with ground water as feed water sample. / Results showed that both water recovery percentage and permeate flux linearly increased with operating pressure. However, intensive pretreatment are required as a result of higher concentration of humic acid and iron in raw feed. Percentages of ion rejection for sodium and calcium are greater than 98 and 99% respectively. The high ion rejections are mainly due to the characteristics of groundwater with low TDS and EC. Sodium and calcium build-up in a small-scale RO system considered appears to be affected by the applied pressure. Build-up of solute in small-scale of RO system has been predicted using the empirical model proposed in this work. Two ions namely sodium and calcium in feed water considered as predominant ions responsible for fouling and scaling on the membrane surface. Four main parameters namely, applied pressure (P), permeate flux (Jw), membrane resistance (Rm), and feed concentration (Cf) are considered which strongly affect the overall membrane performance. The empirical correlations derived from experimental observation among these parameters can be expressed as follows: In Md NaCI = O. 77 In P + 0.67 In Jw + 0.19 In Rm + 0.171n Cf In Md CaCO3= 0.96 In P + 0.75 In Jw + 0.2 In Rm - 0.07 In Cf / The empirical models proposed in this thesis may be useful for predicting the buildup of solute on the membrane surfaces. In the present work, an attempt has been made to estimate the energy consumption and unit cost for desalting of different feed water samples in a small-scale RO system. In RO plants, unit cost of water production from feed water is primarily governed by the energy required for pumping raw water. Estimates of specific energy consumption (SEC) for desalting of sodium chloride, combined sodium and calcium carbonate solutions were found to be in the range of 0.79 - 3.21 and 0.81 - 3.22 kwh/m3 respectively. For groundwater and secondary effluent, they are estimated to 0.63 - 1.71 and 0.79 - 2.02 kWh/m3 respectively. Moreover, energy consumption for different feed water samples was used to estimate the unit cost for water production. Estimation of unit costs for combined sodium chloride and calcium carbonate solution, groundwater, and secondary effluent runs are $2.06 - 3.22, $1.98 - 2.57 and $1.56- 2.66 respectively. In this work, unit cost is still higher due to greater energy consumption .by the pumping system which is required in a small-scale RO operation. Based on the experimental results, it appears that the characteristics of feed water samples affect the membrane performance and their effects must be taken into account in the design of RO units so as to reduce the unit cost for water production. / The findings from the present experimental and modelling work are of practical significance in not only providing the knowledge base in the area of desalination but also paves the way for developing tools for the prediction of build-up of solutes on membrane surface in full scale reverse osmosis operations.

Les sollicitations hydro-climatiques parfois extrêmes que subissent les constructions en terre crue peuvent entraîner des dégradations importantes pouvant conduire à leur effondrement. Ce travail s'inscrit dans le cadre du programme Central Asian Earth de l'UNESCO, en coopération avec le laboratoire CRATerre-ENSAG. Le site de Deshan Kala à Khiva (Ouzbékistan) est retenu pour étudier les mécanismes de transferts d'eau et de sels dans le sol et le mur. Il est instrumenté pour suivre l'évolution des paramètres hydro-climatiques contraignant les transferts. Le modèle de transferts couplés d'humidité et de chaleur considère la gravité et la capillarité pour le transport du liquide et la diffusion pour celui de la vapeur. La densité du liquide est variable selon la concentration en solutés. Les solutés sont transportés par convection-dispersion. La cristallisation/dissolution est une réaction d'ordre un. Les propriétés de transfert des matériaux sont déterminées en laboratoire. Les phénomènes de transfert sont étudiés numériquement. Les simulations monodimensionnelles mettent en évidence la présence d'une zone sèche proche de la surface impliquant l'évaporation de l'eau à l'intérieur du matériau. L'intensité des flux d'humidité et l'état hydrique du système sont influencés par le niveau de la nappe et les conditions atmosphériques. Le sel cristallise dans la zone sèche ou à la surface selon les conditions et le matériau considérés. Les simulations bidimensionnelles permettent d'évaluer l'impact de la qualité de la surface du sol et de la végétation sur les flux d'humidité dans le mur à proximité. Ces résultats ont un intérêt pour la conservation du patrimoine.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv. / Härtill 4 uppsatser.

Diss. (sammanfattning). Uppsala : Sveriges lantbruksuniv. / Härtill 3 uppsatser.

Submitted by (edna.saturno@ufrpe.br) on 2016-07-05T15:37:36Z No. of bitstreams: 1 Erika Socorro Alves Graciano.pdf: 691160 bytes, checksum: faf5b85667aa75d7307d79f2acf9ddb2 (MD5) / Made available in DSpace on 2016-07-05T15:37:36Z (GMT). No. of bitstreams: 1 Erika Socorro Alves Graciano.pdf: 691160 bytes, checksum: faf5b85667aa75d7307d79f2acf9ddb2 (MD5) Previous issue date: 2009-02-05 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Belonging to Leguminoseae Family, peanut is a very important crop to the food industry, because its high oil and protein contents essential for nutrition. The market enlargement due to the high industry demand and mainly the biodiesel production brings news and favorable perspectives to expand this crop in the semi-arid region of Brazilian northeastern. However, the low water availability is the main limiting factor to agriculture expansion in these areas. Although peanut crop shows well adapted to water deficit conditions, there are still so much to be studied to improve its potential and performance in the semi-arid areas. Thus, an experiment was carried out in greenhouse conditions aiming to evaluate some physiological and biochemical parameters of two peanuts cultivars under water deficit. A randomized experimental design was used in a factorial 2 (cultivars) x 3 (water treatments), with six replications. The cultivars studied were BR1 and BRS Havana. The water treatments were: daily watering, five days intervals of watering and water withholding. Growth analysis was accomplished over all the experimental period. At the end of the experiment, leaf water potential and relative water content was measured. For the biochemical analyses, leaf and root tissues were collected to the determination of total soluble carbohydrates, amino acids, protein and free proline. For growth analysis, the plants were separated in leaves, stems and roots to determination of dry matter. Leaf area, root:shoot ratioand biomass allocation were calculated. The obtained data were submitted to variance analysis and the means were compared by Tukey Multiple Range Test (P<0.05). Soluble arbohydrates, proteins, amino acids and free proline contents increased with the water deficiency in the leaves and roots of peanut cultivars. Plants water relations were influenced by water deficit reducing leaf water potential to more negative values. The growth of the peanuts cultivars was reduced proportionally to water availability, with marked varietal differences. The cultivar BR1 is more adapted to water deficiency conditions by showing physiological mechanisms capable to accumulate more organics solutes osmotically actives, reducing its leaf water potential to more negatives values, and for showing less growth alterations. / Pertencente a família Leguminosae, o amendoim é uma cultura muito importante para a indústria alimentícia, por ser constituído de alto teor de óleo e proteínas essenciais à nutrição. A ampliação do mercado tendo em vista a alta demanda pelas indústrias e principalmente a produção de óleo traz novas e favoráveis perspectivas de ampliação dessa cultura na região semi-árida do Nordeste brasileiro. Embora essa cultura mostre-se bem adaptada à condição de deficiência hídrica, principal fator limitante da produtividade, há muito ainda a ser estudado para um melhor aproveitamento do potencial e desempenho dessa cultura no semi-árido. Portanto, foi desenvolvido um experimento em casa de vegetação com objetivo de avaliar alguns parâmetros fisiológicos e bioquímicos de duas cultivares de amendoim submetidas à deficiência hídrica. O delineamento experimental utilizado foi o inteiramente casualizado, em um arranjo fatorial de 2 x 3 (Cultivares x Tratamentos hídricos), com seis repetições. As cultivares estudadas foram BR1 e BRS Havana, e os tratamentos hídricos utilizados foram: rega diária, rega a cada cinco dias e suspensão de rega. As análises de crescimento foram realizadas durante todo o período experimental. No final do experimento, foi avalia as relações hídricas, mensurando o potencial hídrico foliar e determinado o conteúdo relativo de água foliar. Para as análises bioquímicas, foram coletadas amostras das folhas e das raízes para a determinação dos carboidratos solúveis, proteínas solúveis, aminoácidos livres totais eprolina livre. Também foi determinada a área foliar e a matéria seca, com esses dados calculou-se a alocação de biomassa para as folhas, hastes e raízes e a relação raiz/parte aérea.Os dados obtidos foram submetidos à análise de variância e as médias comparadas pelo teste de Tukey. Os teores de carboidratos solúveis, proteínas solúveis, aminoácidos livres e prolina livre aumentam com a deficiência hídrica nas folhas e raízes das cultivares de amendoim. As relações hídricas das plantas são influenciadas com a deficiência hídrica, reduzindo o potencial hídrico foliar a valores mais negativos. O crescimento das cultivares de amendoim é reduzido proporcionalmente com a disponibilidade hídrica, com marcada diferença varietal. A cv. BR1 é mais adaptada às condições de deficiência hídrica, por apresentar mecanismos fisiológicos capazes de acumular mais solutos orgânicos osmoticamente ativos, reduzir seu potencial hídrico a valores mais negativo e por sofre menores alterações no crescimento.

A modelagem da dinâmica de solutos no solo tem se mostrado uma ferramenta essencial, pois permite simular cenários e prever impactos ao meio ambiente associados ao manejo inadequado de fertilizantes agrícolas. Na zona radicular das culturas a parametrização do transporte de solutos, bem como a parametrização física do solo, são de difícil determinação tornando a sua modelagem onerosa e imprecisa. Portanto, a presente pesquisa teve como objetivo avaliar a performance do modelo SWAP (Soil, Water, Atmosphere and Plant), em simular a extração da solução do solo pela cultura do milho, em ambiente protegido. O ambiente de estudo ficou restrito à rizosfera da cultura do milho ao longo de seu ciclo de desenvolvimento, mediante a aplicação de uma solução de nitrato de potássio via água de irrigação. Para isso, conduziu-se um experimento em ambiente protegido, cujo cultivo do milho foi feito em 18 lisímetros de drenagem de 500L com plantio de duas covas por lisímetro (plantio em 22/11/2014 e colheita em 22/02/2015). Os valores de umidade volumétrica do solo e de condutividade elétrica da solução do solo foram registrados pela TDR (Time Domain Reflectometry), sendo monitorados em 4 profundidades ao longo da secção transversal das raízes (5, 15, 25 e 35 cm). Também foram monitoradas variáveis agrometeorológicas a fim de se descrever as condições experimentais. Os valores simulados pelo modelo SWAP foram confrontados com os dados observados, registrados pela TDR. A avaliação da performance do modelo foi feita pelo emprego do índice de concordância (Id), índice de avaliação de modelos (E), raíz quadrada média do erro (RMSE) e coeficiente de determinação. Diante dos resultados obtidos, percebeu-se pelo monitoramento agrometeorológico que o ciclo da cultura se deu em condições de anomalias climáticas, isso de certa forma influenciou na extração de água pela cultura. A simulação da extração de água na rizosfera do milho pelo modelo SWAP demonstrou uma satisfatória performance do modelo, o qual apresentou resultado pelos índices de avaliação valores superiores a 0,7 e índices de concordância superiores a 0,9 para todas as camadas monitoradas. O erro quadrático médio foi inferior a 0,009 cm3 cm-3 para todas as camadas, apesar de ter nas camadas mais profundas uma atenuação qualitativa na simulação. O movimento da extração da solução do solo na rizosfera, em especial, nas camadas superficiais apresentaram resultados satisfatórios com índices de avaliação de modelos de 0,659 e 0,596 e índices de concordância de 0,913 e 0,834, respectivamente, para as camadas de 5 e 15 cm de profundidade. Já para as camadas mais profundas não se observou boa aderência do valor simulado aos dados. O coeficiente de extração relativa da solução do solo pelo milho apresentou valor de 16%. Assim, o modelo SWAP mostrou-se satisfatório na simulação do movimento da solução do solo na zona radicular da cultura do milho, mesmo sob condições atmosféricas extremas. Não obstante, seu desempenho foi prejudicado para as simulações em camadas inferiores, onde foi observada uma baixa variação do conteúdo de água e concentração de sais no solo. / The modeling of solute dynamics in soil is an essential tool for simulating scenarios and predicting environment impacts associated with inadequate management of fertilizers. Solute transport parameter and soil physical parameters in the vadose zone are difficult to determine, causing modeling to be expensive and imprecise. This research, therefore, was set up to evaluate the effectiveness of the SWAP (Soil, Water, Atmosphere and Plant) model to simulate soil solution uptake by corn under controlled environmental conditions. The study consisted of applying a potassium nitrate solution in irrigation water to maize rhizosphere throughout its development cycle. The experiment was conducted in a greenhouse, in which maize was planted on 11/22/2014 and harvested on 02/22/2015 in eighteen 500L drainage lysimeters.The soil moisture values and electrical conductivity of soil solution were registered by TDR (Time Domain Reflectometry) at four depths (5, 15, 25 and 35 cm) along the cross-section of the root. Environmental variables were also monitored in order to characterize the experimental conditions. Values simulated by the SWAP model were compared with observed data recorded by the TDR. Model performance was evaluated by the use of the Concordance Index (Id), the Model Assessment Index (E), Root Mean Square Error (RMSE), and Coefficient of Determination. As the experiment was conducted under controlled conditions, the water uptake patterns might not be reflective of uptake patterns under normal weather conditions. The simulation of water extraction in the rhizosphere of corn by SWAP model matched observed values, with indices greater than 0.7 and concordance rates of over 0.9, for all monitored layers. The RMSE was less than 0.009 cm3 cm-3 for all layers. The concentration of extracts of the soil solution in the rhizosphere, in particular in the top two layers, were satisfactorily simulated with model evaluation indexes of 0.659 and 0.596, and concordance rates of 0.913 and 0.834, respectively, for the 5 and 15 cm layers. For the deeper layers, there was little correlation between the observed and simulated value. The relative extraction coefficient of soil solution for corn was 16%. Thus, the SWAP model satisfactorily simulated soil solution movement in the upper layers of the vadose zone of maize, even under extreme weather conditions. However, the model did not perform as well in the lower layers performance was impaired for the simulations in lower layers, which had low variation in the observed water content and salt concentration in the soil.

Changing climate in combination with growing world populations mean that there is growing need for plants to be grown on land that is currently considered marginal for agriculture. Sorghum is a C4 plant that serves as an important food crop in Africa and India. It is also known to be highly drought tolerant but the mechanisms responsible for this tolerance are unclear. The overall aim of this study was to understand the drought tolerance mechanisms that enable the plant to maintain leaf function for a long time during water deficit. In Chapter 2 of this thesis, I studied the underlying physiological mechanisms for tolerating drought in two sorghum varieties with differing degrees of drought tolerance compared to a closely related species, Zea mays. During progressive drought, the more tolerant sorghum variety Samsorg 17 maintained net CO2 assimilation and photochemistry longest relative to the less tolerant Samsorg 40 and Zea mays. Differences were also seen in stomatal aperture, stomatal density, total chlorophyll content, chl a:b and A/Ci curve responses with maize more affected than the sorghum varieties. In Chapter 3, I identified novel drought tolerance mechanisms in the sorghum varieties. The less tolerant Samsorg 40 lost PsbA (D1) and Rubisco proteins and reengineered its photosynthetic apparatus to accumulate amino acids and sugars in order to maximise survival under drought. Samsorg 17 maintained photosynthetic proteins notably PsbA (D1) and Rubisco and accumulated high constitutive sugar content allowing for the maintenance of transpiration and photosynthesis. The two sorghum varieties had strikingly contrasting approaches of tolerating drought as demonstrated in Chapter 3. In Chapter 4, the aim was to characterise biochemical and metabolic changes that occur in response to drought. In particular, to identify sugars that are accumulated constitutively in Samsorg 17 and nitrogen sinks for lost N in Samsorg 40. My findings indicated a contrasting response in terms of sugar content in Samsorg 17 but support for amino acids as N sinks in Samsorg 40 as reported earlier. Sugars, sugar alcohols, lipids, organic acids, heat shock proteins and dehydrins were generally higher or more induced in Samsorg 17 relative to Samsorg 40. Samsorg 40 rather made amino acids. The implications of my findings and future work arising from this study were discussed in detail in the final chapter. In conclusion, in this thesis, it was demonstrated that closely related plants can have mechanistically different physiological and biochemical mechanisms for responding to drought.